Emails getting deferred

I have 2 ZCS servers in the same network one is runnning on UBUNTU and other is on FEDORA,both the email servers have two different domain whenI try to send email from one domain to other domain my emails go deferred any solyuion for this..

I have 2 ZCS servers in the same network one is runnning on UBUNTU and other is on FEDORA,both the email servers have two different domain whenI try to send email from one domain to other domain my emails go deferred any solyuion for this..

As usual the question about DNS A & MX records, do you have any and are they pointing to the server?

This is the error which I got in my logs.
DNS is working properly I have created all the records in DNS

You're only partly answering my questions, I asked you about the services running, firewall and SElinux and you've not even mentioned them. You've given no evidence to show the DNS is working correctly - merely saying 'it works' doesn't give any evidence that it's set-up correctly. I would like some more information than you're currently providing, it's Friday and my telepathic powers don't work too good just before the week-end.